According to studies carried out by the inventors of the present invention, existing signal transmission system technology is as described in the following.
In recent years, the clock frequency for operating the LSI chip has reached 1.5 GHz. However the maximum frequency of the lines connected to the chips that handle these signals is a mere 530 MHz. Thus the band width for incorporating the signals into the LSI is insufficient to meet the demands LSI. In order for the signal processing of LSI to be carried out smoothly, cache memory such as logic chips or memory chips must be implanted in order to solve the problem of insufficient band width.